The term “immersive display” is used in virtual reality discussions to refer to a display that at least partially surrounds a viewer. Typically consisting of large, curved screens (possibly as long as 24 feet or more in length), an image projected thereupon completely fills the peripheral vision of a viewer. The term “spatially immersive wall” is sometimes applied to such screens.
Such displays, often also referred to as wide field of view (WFOV) displays, are widely used in training simulators to provide realistic visual imagery to a person being trained in the simulator. Many other applications exist for such immersive displays. Well known applications include control centers (e.g., traffic, power, shipboard, emergency service, factory operations, process control, military, etc.).
In immersive displays and other similar applications, it is, therefore, highly desirable to project or display a unified, composite image formed from image segments originating at one or more image sources (e.g., projectors). Often, such composite images must be projected onto a non-planar surface, for example onto a screen curved along at least one dimension. Such images may be produced by either front or rear projection onto the screen. Because of screen imperfections, projector anomalies, projector/screen alignment differences, etc., the multiple images, if projected “raw,” do not yield an acceptable composite image. Further, color balance and brightness differences among multiple projectors further detract from a seamless, contiguous, composite image.
It is, therefore, common practice in installations designed to exhibit such composite images, to align and calibrate system components to overcome image distortions introduced from the aforementioned sources. Such calibration and alignment procedures often suffer from one or more common shortcomings. For example, most calibration and alignment procedures of the prior art are either extremely time consuming and/or inaccurate. Further, minute changes in one or more system components often requires recalibration.
Traditionally, a number of instruments are used for alignment of immersive visual displays. Transits may be used to verify absolute locations of display imagery with respect to design specifications. Often, at least two transits are needed for calibrating at a price in excess of $20K each. Luminance meters may be used to measure colorimetry for channel matching and edge blending. Large amounts of manual setup, measurement, and interpretation, followed by manual and/or computer based calculations provide feedback to the image source to correct parameters.
Recent additions to high end projector devices allow for individual channel alignment. Such projectors still lack the ability to handle cross channel parameter measurement and adjustment in highly immersive environments with many adjacent display channels.
As projector and associated image processing costs continue to fall, immersive displays are utilizing more and more channels, thereby making setup and maintenance costs for such systems increasingly higher. Each added channel brings increased complexity and more need for aligning and blending image segments in the display.